A device (1) for covering and/or reconstructing a bone defect site (2) and a method for producing a cap (4) of a covering device for a bone defect site (3) are proposed, wherein the device (1) for covering and/or reconstructing a bone defect site (2) consists of a cap (4) (moulded shell, rigid shell, shaped body) and of at least one fixing means (5) for fixing the cap (4) on a bone, and the cap (4) is distinguished by having a dimensionally stable (rigid) nature, and a wall (9) of the cap (4) directed towards the bone defect or a wall (11) of the cap (4) directed away from the bone defect corresponds to the shape of the regenerated bone.
